Mostrando entradas con la etiqueta Nanoelectrónica. Mostrar todas las entradas
Mostrando entradas con la etiqueta Nanoelectrónica. Mostrar todas las entradas

lunes, 3 de junio de 2013

Popular Scientist. Aydogan Ozcan (LUCAS Inventor)

ORIGINAL: UCLA MAGAZINE
By Robin Keats
Apr 1, 2013


UCLA Associate Professor of Electrical and Bioengineering Aydogan Ozcan is one of the world's "Brilliant 10" scientists, as proclaimed by Popular Science magazine. Ozcan is the director of the Bio-and Nano-Photonics Laboratory at the UCLA Henry Samueli School of Engineering and Applied Science, where he leads a team of students in creating breakthrough—and inexpensive—technological devices that bring the frontiers of medicine to ordinary individuals.
Photo by: Clara Richmond.
We could begin with any one of more than a dozen startlingly original inventions to frame the contributions of Aydogan Ozcan, but let's start with the crowd-sourced bio-game he and his team of researchers created to diagnose malaria. One thousand online gamers from around the world were directed to identify, then "kill" or "bank," infected red-blood cells that appeared on their screens as electronic images. Their success rate at identifying the disease was very comparable to that of medical experts. This decidedly non-expert methodology is designed for use in developing nations where hugely expensive diagnostic equipment is unavailable.

And then there is BigFoot, the name Ozcan gave to the monitoring software he pioneered that allows diabetes patients and others with chronic foot ailments to track their conditions at home using a conventional flatbed scanner and a PC.

These are just two of an apparently endless lineup of incredible ideas that spring from the mind of the 34-year-old scientist who already holds 22 patents, with more than 15 pending, for inventions in wide-field and lens-less imaging, nonlinear and fiber optics, critical coherence tomography and nanoscopy.

Ozcan's self-described "prize child," though, is LUCAS, an acronym for "Lens-less, Ultra-wide-field blood Cell monitoring Array platform based on Shadow imaging." It turns a cell phone into a diagnostic device by clipping on a gadget that combines an LED light, a spatial filter and a slot for a medical slide. Information is gathered by the device, which sends it off to diagnosticians anywhere in the world. Bring LUCAS into the jungle where people get little or no medical attention, and voila! Expert diagnosis.

Through the device, millions of people in such remote areas as sub-Saharan Africa who would otherwise go undiagnosed will be screened or monitored for malaria, and eventually for tuberculosis and HIV. It will also help prevent waterborne illnesses that kill about 5 million people a year. And the cost to clip LUCAS onto your cell phone? Five to 10 bucks.

No 'Aha' Moment
Ozcan was born in Istanbul, Turkey, in 1978. His father was a government worker, his mother a housewife. His education began in the small, Black Sea city of Sinope, which also gave the world Diogenes, founder of Cynic philosophy. "My family moved around a lot," he says. "Five different schools for the five years of elementary school we have in Turkey ... I think those moves caused me to develop skills that have helped me quickly adapt to things."

Ozcan went to Bilkent University in Ankara for his bachelor's degree. He earned a master's degree and Ph.D. at Stanford University, followed by two years in Boston on the research faculty of Harvard Medical School's Wellman Center for Photomedicine. Ozcan joined UCLA as an assistant professor in 2007.

What turned him onto scientific innovation? "There was," he says, "no 'aha' moment." But as early as his freshman year in high school, "the idea of proving something and learning the framework of proofs was so unique," he recalls. "That's when I said 'I love it' [and] thought I'd be in a profession that allows for the creation of useful things.
Add caption
For his breakthrough medical diagnostic inventions, Ozcan has been honored by NASA, the U.S. Department of State, the Gates Foundation, National Geographic and Popular Mechanics, among other institutions and publications. In the photo above, he is holding a prototype of his LUCAS device in his lab.

Teaching Invention "Being a scientist and going to the frontier of knowledge requires a lot of dedication, a lot of small things put together," he says. "I insist that my students know that those who are successful in this profession are the ones who learn how to cope with failures. You improve from rejection; you write a new manuscript; you try again. Some people would say, 'It's enough.' I won't play that game."

It has to be that way, Ozcan says of his role as an educator. "Within the school of engineering, the function of a professor is to create new information and new technologies. You also have to train the next generation of engineers and scientists, so that new know-how is continually created to make life simpler."

Ozcan adds, "The definition of engineering, for me, is to make life simpler and better. That's the most important thing that differentiates an engineer's mind from that of a physicist. A physicist is looking at interesting questions, but not how a combination of disciplines could be applied to create things that will enhance life. That's the intersection of science and engineering and I want to be, professionally, at that juncture. Engineers need to be very multidisciplinary. That's what I stress in my lab."

Creating Invention

The man whose world involves complex technologies like optics, photonics and imaging has a simple vision of his own future as an innovator. "It's like a single picture," he says. "You can give yourself 10 or 15 years to paint it, but then it's going to be something you can admire. That's how I take my career. I'm in the middle of that picture now [with] the expansion of the cell phone into an array of telemedicine tools."

Cell phones, he points out, have better graphics processors than IBM supercomputers had in the late 1980s. "There are already 5 billion cell phones in use," he explains. "We manufacture 2 billion of them every year … There will be more of them everywhere on the planet."

With this phenomenal global network of smart gadgets, he points out, computation is almost free.

"Because cell-phone use is so ubiquitous and inexpensive," he adds, "I can rely on it … to design new microscopes and micro-analysis tools that look at bodily fluids using technology attached to the cell phone or running on it."

The "Nano Internet" and Beyond
The young scientist's next challenge is already obvious to him. He foresees spending the next decade or so building the "Nano Internet," which he describes as "the development of these personal micro-analysis tools [that] give us something more valuable than the tools themselves."

What he envisions are millions of his tiny devices interconnecting and streaming personal health information in real time, from brainwaves to blood-pressure counts.

"If my lab and others like it do our work well," he predicts, "then we'll have this kind of Nano Internet. The opportunities that lie ahead of us, with our eyes, with our information, channeled into the micro and Nano worlds."

These and other trails yet unimagined will be blazed from Westwood. "UCLA maintains and extends such vision," says Ozcan. "It's got everything I need to fulfill whatever I dream."

lunes, 25 de marzo de 2013

Nanowire solar cells raises efficiency limit


Scientists from the Nano-Science Center at the Niels Bohr Institut, Denmark and the Ecole Polytechnique Fédérale de Lausanne, Switzerland, have shown that a single nanowire can concentrate the sunlight up to 15 times of the normal sun light intensity. The results are surprising and the potential for developing a new type of highly efficient solar cells is great.
Nanowire crystals used as the solar cells. SEM (Scaning Electron Microscope) image of GaAs nanowire crystal grown on a Silicon substrate
- Due to some unique physical light absorption properties of nanowires, the limit of how much energy we can utilize from the sun's rays is higher than previous believed. These results demonstrate the great potential of development of nanowire-based solar cells, says PhD Peter Krogstrup on the surprising discovery that is described in the journal Nature Photonics.

The research groups have during recent years studied how to develop and improve the quality of the nanowire crystals, which is a cylindrical structure with a diameter of about 10,000 part of a human hair. The nanowires are predicted to have great potential in the development not only of solar cells, but also of future quantum computers and other electronic products.

- It turns out that the nanowires naturally concentrate the sun's rays into a very small area in the crystal by up to a factor 15. Because the diameter of a nanowire crystal is smaller than the wavelength of the light coming from the sun it can cause resonances in the intensity of light in and around nanowires. Thus, the resonances can give a concentrated sunlight, where the energy is converted, which can be used to give a higher conversion effeciency of the sun's energy, says Peter Krogstrup, who with this discovery contributes to that the research in solar cell technology based on nanowires get a real boost.
The figure shows that the sun's rays are drawn into a nanowire, which stands on a substrate. At a given wavelength the sunlight is concentrated up to 15 times. Consequently, there is great potential in using nanowires in the development of future solar cells. (credit: Niels Bohr Institute)

New efficiency limit
The typical efficiency limit - the so-called "Shockley-Queisser Limit" - is a limit, which for many years has been a landmark for solar cells efficiency among researchers, but now it seems that it may be increased.

- It's exciting as a researcher to move the theoretical limits, as we know. Although it does not sound like much, that the limit is moved by only a few percent, it will have a major impact on the development of solar cells, exploitation of nanowire solar rays and perhaps the extraction of energy at international level. However, it will take some years years before production of solar cells consisting of nanowires becomes a reality, says Peter Krogstrup who just completed his PhD at the Niels Bohr Institute, University of Copenhagen.

The research is conducted in collaboration with the Laboratory des Matériaux Semiconducteurs, Ecole Polytechnique Fédérale de Lausanne, the Foundation and the company SunFlake A / S. Their scientific findings work support results published in the journal Science in January. Here, a group of researchers from Lund, showed that the sun’s rays was sucked into the nanowires due to the high amount of power that their solar cell produced.

Article in Nature Photonics >>

jueves, 24 de mayo de 2012

Availability of hydrogen controls chemical structure of graphene oxide

ORIGINAL: PhysOrg
The image shows a sample of graphene oxide produced by the oxidation of epitaxial graphene on silicon carbide. Credit: Georgia Tech Photo: Gary Meek

A new study shows that the availability of hydrogen plays a significant role in determining the chemical and structural makeup of graphene oxide, a material that has potential uses in nano-electronics, nano-electromechanical systems, sensing, composites, optics, catalysis and energy storage.

The study also found that after the material is produced, its structural and chemical properties continue to evolve for more than a month as a result of continuing chemical reactions with hydrogen.

Understanding the properties of graphene oxide – and how to control them – is important to realizing potential applications for the material. To make it useful for nano-electronics, for instance, researchers must induce both an electronic band gap and structural order in the material. Controlling the amount of hydrogen in graphene oxide may be the key to manipulating the material properties.

"Graphene oxide is a very interesting material because its mechanical, optical and electronic properties can be controlled using thermal or chemical treatments to alter its structure," said Elisa Riedo, an associate professor in the School of Physics at the Georgia Institute of Technology. "But before we can get the properties we want, we need to understand the factors that control the material's structure. This study provides information about the role of hydrogen in the reduction of graphene oxide at room temperature."